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Utilization of Reconstituted Whey Powder and Microbial Transglutaminase in Ayran (Drinking Yogurt) Production 

Ceren Akal*orcid tiny, Celalettin Koçakorcid tiny, Nazlı Kancaorcid tiny and Barbaros Özerorcid tiny

1Department of Dairy Technology, Faculty of Agriculture, Ankara University, Sehit Omer Halisdemir Cad., 06110, Diskapi, Ankara, Turkey

Article history:

Received: 12 January 2021

Accepted: 15 February 2022

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fermented products; whey; transglutaminase; SDS-PAGE; volatile profile; rheology



Research background. In industrial Ayran production, milk is diluted to the desired protein level (2 % (m/V)) prior to fermentation by yogurt starter cultures. The dilution of milk to desired protein level may well be achieved by means of partially replacement of cheese whey either in native or in reconstituted form with potable water. This may be an alternative way of protein recovery from cheese by-products as well as reducing the production costs since less milk is used in Ayran production. On the other hand, the balance between milk caseins and whey proteins is disturbed when cheese whey is added to Ayran milk which likely leads to a time-dependent phase separation during cold storage. Modification of Ayran matrix by means of enzymatic-crosslinking of proteins may be a solution to overcome this potential physical instability in Ayran. This topic has not been explored to date, and the present study was designed to investigate the possibilities of utilization of reconstituted whey powder (RWP) and microbial transglutaminase (mTG) in Ayran production. 

Experimental approach. Eight different groups of Ayran samples namely group A (prepared by partially diluting milk with RWP to meet 5 % (A5), 10 % (A10) or 15 % (A15) of total protein concentration of the product), group B (prepared by adding microbial transglutaminase (0.5 U/g protein) to group A samples (B5+Tg, B10+Tg and B15+Tg)) and group C (control samples treated with (CTg) or without (C) mTG addition and contained no RWP) were produced. The gross composition, physical (phase separation and viscosity), chemical (volatile and peptide profiles and SDS-PAGE electrophoresis patterns) and sensory properties of the samples were evaluated throughout 15 days of storage with weekly intervals.

Results and conclusions. The partial replacement of RWP with potable water in Ayran led to increases in dry matter and serum protein contents of the products. Using RWP in Ayran production increased the phase separation slightly. Incorporation of mTG affected the physical properties of the Ayran samples positively and prevented phase separation at a satisfactory level. SDS-PAGE electrophoretograms revealed that cross-linking between proteins triggered by mTG formed intense bonds at high molecular mass regions. The remaining parameters were not affected by mTG. Results revealed that the samples A10 and BTG+10 were determined as the formulations with the highest commercialization potential.

Novelty and scientific contribution. Utilizing RWP in the production of Ayran to reduce the protein content of the final product to the desired concentration is a new approach. Since fully replacement of RWP with potable water in diluting milk to reach 2 % (m/V) protein concentration likely leads to sensory problems in the product, possibilities of partly replacement of potable water by RWP was sought. A time-dependent phase separation is the major challenge of industrial Ayran production. This physical problem was largely eliminated by means of mTG-mediated cross-linking of milk proteins. The proposed novel Ayran production method offers dairy industry to reduce production costs as well as contributing to sustainability in milk production since less volume of milk is used to reach desired protein concentration in the final product.

*Corresponding author: +905545385216

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